Drive It Forever
Q. I own a supercharged 1992 Buick Park Avenue Ultra that I bought about four years ago. The manual says to use premium gasoline, but the dealer says that they never put premium in these cars and that it isn't necessary if the engine doesn't ping.
Do you agree?
A. Not exactly - though, with the supercharger, there is enough cylinder pressure at wide-open throttle to cause detonation using low-octane gas.
Your engine, like virtually all modern, fuel-injected engines, has a knock sensor. It's a small microphone bolted to the cylinder head that listens for the first sign of engine knock and signals the fuel-injection computer when it occurs. The engine computer then retards the ignition timing and enriches the fuel/air mixture to prevent knocking. This keeps the detonation from melting holes in the tops of your pistons, which would pretty much destroy the engine.
When the car's computer rolls back the timing, engine performance and economy are substantially reduced. You bought a supercharged car expecting a certain level of performance, and you won't get it running cheap gas.
Moreover, the reduced fuel economy will offset much of the savings you'll get from using lower-grade fuel.
Q. My windshield wiper goes past the edge of the glass at the end of the upward stroke.
I have to change the wiper refill every couple of months or so. I pulled the wiper arm off the drive gear, thinking that I could turn it one tooth counterclockwise and index it back to the proper horizontal or "stop" position, but the drive gear is pressed onto the shaft.
Not only that, but the wiper arm has a notch that mates with a tang on the drive gear, preventing you from putting the arm on in any other position.
Is there a fix?
A. I've seen this before. You'll have to bend the arm. Take the arm off the car, put it in a vise and muscle it over an inch or so.
Here's another wiper problem:
Q.I was standing next to my car when my wife hit the windshield-washer button and sprayed smelly, slippery blue stuff onto my best suit. Most of the fluid went over the top of the window and wet down the roof.
I tried to use a pair of needle-nosed pliers to realign the sprayer, but all I did was gouge the plastic.
How can I make the fluid spray onto the windshield, where it belongs?
A. It is astonishingly easy, actually.
The nozzles are built like little ball-and-socket joints. Take a dressmaker's pin or a sewing needle and stick it into the nozzle. Use that pin like a joystick to move the nozzle back to where it belongs.
Q. I own a 1995 Honda Odyssey LX, with a 2.2-liter VTEC engine. It has an automatic transmission-fluid cooler routed through the radiator. The radiator fluid has become thick and brown.
Any prognosis? The engine temperature is OK while running, but shifting is jerky.
A. The transmission cooler is leaking fluid into the coolant, and probably leaking some coolant back into the transmission.
You need to replace that radiator today, if not sooner. Then have the cooling system caustic-flushed to remove any remaining traces of the fluid.
Get the transmission flushed immediately, because any traces of coolant will do bad things in there, especially to the organic facings of the clutches. Simply draining and refilling isn't good enough. Find a shop with one of those machines that hooks up to the transmission cooler lines and purges 100 percent of the fluid.
Then I'd drive about 20 miles, drop the transmission pan and change the filter and fluid again.
Mike Allen is a senior editor for Popular Mechanics magazine. Questions should be sent via e-mail to driveit@nytimes.com. 